This invention relates to a process for the catalytic hydrogenation of 4-nitroso-diphenylamine to form 4-amino diphenylamine.
It is already known that 4-nitroso-diphenylamine can be hydrogenated in isopropanol in the presence of a palladium-carbon catalyst (British Pat. No. 935,303). It is also known that the potassium or sodium salt of 4-nitroso-diphenylamine can be hydrogenated in an aqueous solution using palladium or platinum catalysts in conjunction with benzene (German Pat. No. 1,266,766). It is also known that a 2-component catalyst containing nickel and manganese can be used for catalytic hydrogenation in aqueous solution (DOS No. 1,941,008). However, the use of Raney nickel as a catalyst in the catalytic hydrogenation of 4-nitroso-diphenylamine is not known.